Integration of Multiple Components in Polystyrene-Based Microfluidic Devices Part I: Fabrication and Characterization.

Integration of multiple components in polystyrene-based microfluidic devices part I: fabrication and characterization.

Filed under: Drug and Alcohol Rehabilitation

Analyst. 2012 Nov 2;
Johnson AS, Anderson KB, Halpin ST, Kirkpatrick DC, Spence DM, Martin RS

In Part I of a two-part series, we describe a simple and inexpensive approach to fabricate polystyrene devices that is based upon melting polystyrene (from either a Petri dish or powder form) against PDMS molds or around electrode materials. The ability to incorporate microchannels in polystyrene and integrate the resulting device with standard laboratory equipment such as an optical plate reader for analyte readout and pipets for fluid propulsion is first described. A simple approach for sample and reagent delivery to the device channels using a standard, multi-channel micropipette and a PDMS-based injection block is detailed. Integration of the microfluidic device with these off-chip functions (sample delivery and readout) enables high-throughput screens and analyses. An approach to fabricate polystyrene-based devices with embedded electrodes is also demonstrated, thereby enabling the integration of microchip electrophoresis with electrochemical detection through the use of a palladium electrode (for a decoupler) and carbon-fiber bundle (for detection). The device was sealed against a PDMS-based microchannel and used for the electrophoretic separation and amperometric detection of dopamine, epinephrine, catechol, and 3,4-dihydroxyphenylacetic acid. Finally, these devices were compared against PDMS-based microchips in terms of their optical transparency and absorption of an anti-platelet drug, clopidogrel. Part I of this series lays the foundation for Part II, where these devices were utilized for various on-chip cellular analysis.
HubMed – drug


Solid-state characterization of lacidipine/PVP K(29/32) solid dispersion primed by solvent co-evaporation.

Filed under: Drug and Alcohol Rehabilitation

Int J Pharm Investig. 2012 Apr; 2(2): 90-6
Mukharya A, Chaudhary S, Mansuri N, Misra AK

Lacidipine (LCDP) is a 1,4-dihydropyridine derivative categorized as an anti-hypertensive Ca2+ channel blocker having very low solubility, and thus very low oral bioavailability, which presents a challenge to the formulation scientists. Homogeneous distribution of poorly water-soluble drugs like LCDP in polyvinylpyrrolidone (PVP), a hydrophilic carrier, is definitely a suitable way to improve the bioavailability of such drugs.The aim of the study was to develop a combined thermal, imaging, and spectroscopic approach, and characterize physical state, dissolution behavior, and elucidation of drug-PVP interaction in LCDP/PVP solid dispersion (SD) using differential scanning calorimetry (DSC), X-ray diffractometry (XRD), fourier transform infrared (FTIR) spectroscopy, and hot stage microscopy (HSM), which is the prerequisite for the development of a useful drug product.Dissolution studies of LCDP and its physical mixture with PVP showed less than 50% release even after 60 min, whereas SD of LCDP/PVP ratio of 1:10% w/w showed complete dissolution within 45 min. DSC and powder XRD proved the absence of crystallinity in LCDP/PVP SD at a ratio of 1:10% w/w. The FTIR spectroscopy indicated formation of hydrogen bond between LCDP and PVP. In the SD FTIR spectra, the -NH stretching vibrations and the -C=O stretch in esteric groups of LCDP shift to free -NH and C=O regions, indicating the rupture of intermolecular hydrogen bond in the crystalline structure of LCDP.Solid-state characterization by HSM, DSC, XRD, and FTIR studies, in comparison with corresponding physical mixtures, revealed the changes in solid state during the formation of dispersion and justified the formation of high-energy amorphous phase.
HubMed – drug


Formulation and evaluation of floating matrix tablet of stavudine.

Filed under: Drug and Alcohol Rehabilitation

Int J Pharm Investig. 2012 Apr; 2(2): 83-9
Prajapati PH, Nakum VV, Patel CN

The purpose of the study was to prolong the gastric residence time of stavudine by designing its floating tablets and to study the influence of different polymers on its release rate.The floating mix matrix tablets of stavudine were prepared by melt granulation method. Beeswax was used as hydrophobic meltable material. Hydroxypropyl methylcellulose (HPMC), sodium bicarbonate, and ethyl cellulose were used as matrixing agent, gas generating agent, and floating enhancer, respectively. The prepared tablets were evaluated for physicochemical parameters such as hardness, weight variation, friability, floating properties (floating lag time, total floating time), drug content, stability study, and in vitro drug release. The drug- polymer interaction was studied by Differential Scanning Calorimetry (DSC) thermal analysis and Fourier transform infared (FT-IR).The floating lag time of all the formulations was within the prescribed limit (<3 min). All the formulations showed good matrix integrity and retarded the release of drug for 12 h except the formulation F5.The concentration of beeswax (X(1)), HPMC K(4)M (X(2)), and ethyl cellulose (X(3)) were selected as independent variables and drug release values at 1 (Q(1)), at 6 (Q(6)) and at 12 h (Q(12)) as dependent variables. Formulation F7 was selected as an optimum formulation as it showed more similarity in dissolution profile with theoretical profile (similarity factor, f(2) = 70.91). The dissolution of batch F7 can be described by zero-order kinetics (R(2) =0.9936) with anomalous (non-Fickian) diffusion as the release mechanism (n=0.545). There was no difference observed in release profile after temperature sensitivity study at 40°C/75% relative humidity (RH) for 1 month.It can be concluded from this study that the combined mix matrix system containing hydrophobic and hydrophilic polymer minimized the burst release of drug from the tablet and achieved a drug release by zero-order kinetics, which is practically difficult with only hydrophilic matrix. HubMed – drug


Formulation and evaluation of an in situ gel-forming ophthalmic formulation of moxifloxacin hydrochloride.

Filed under: Drug and Alcohol Rehabilitation

Int J Pharm Investig. 2012 Apr; 2(2): 78-82
Mandal S, Thimmasetty MK, Prabhushankar G, Geetha M

The aim of the present investigation is to prepare and evaluate in situ gel-forming ophthalmic drug delivery system of moxifloxacin hydrochloride.Sodium alginate, a novel ophthalmic gel-forming mucoadhesive polymer, which gets converted to gel in the presence of divalent-cations (calcium ion) present in the lachrymal fluid, was used as the gelling agent. Hydroxy propyl methyl cellulose (HPMC) is a mucoadhesive polymer used as viscosity enhancer. Suitable concentrations of buffering agents were used to adjust the pH to 6.5. All the formulations were sterilized in an autoclave at 121°C for 15 minutes. The formulations were evaluated for clarity, pH measurement, gelling capacity, drug content estimation, rheological study, in vitro diffusion study, antibacterial activity, isotonicity, and eye irritation study.The developed formulations exhibited sustained release of drug from formulation over a period of 10 hours thus increasing residence time of the drug. The optimized formulations were tested for eye irritation on albino rabbit (male). The formulations were found to be non-irritating with no ocular damage or abnormal clinical signs to the cornea, iris or conjunctiva observed.These in situ gelling systems containing gums may be a valuable alternative to the conventional systems.
HubMed – drug



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